Vacuum Assisted Filtration

ABSTRACT

An apparatus includes a chemical filter fluidly coupled between a source for a processing solution and a nozzle to dispense the processing solution. The chemical filter is configured to filter the processing solution from the source. The apparatus may include a vacuum pump that is configured to apply a vacuum to the chemical filter. The apparatus may include a valve system configured to operate in a first operating state and a second operating state, where in the first operating state the valve system is configured to couple the source to the chemical filter and block the vacuum to the chemical filter, and where in the second operating state the valve system is configured to couple the vacuum to the chemical filter and block the source to the chemical filter.

TECHNICAL FIELD

The present invention relates generally to a system and method forsemiconductor equipment, and in particular embodiments, to vacuumassisted filtration.

BACKGROUND

In the manufacturing of semiconductor devices, a filter is used withinthe chemical dispense system to remove foreign matter (i.e., smallparticles, debris, particulates, etc.) from processing solutions. Thefiltration system ensures foreign matter does not reach the dispenseline and make its way onto the wafer.

In addition to foreign matter that finds its way into the filtrationsystem, trapped air—which gives rise to the formation of bubbles—canalso be problematic. Taking into account the scaling of criticaldimensions (CDs) and increased miniaturization of features withinsemiconductor devices, even fine bubbles that were not once a problemcan become troublesome. In the event the bubbles are not removed fromthe filtration system, and instead make their way through the dispenseline and onto the wafer, yield can be heavily impacted.

Hence, strategies to improve the filtration equipment becomeincreasingly needed. However, current suggestions to improve filtrationequipment involve lengthy installation processes, extended equipmentdowntimes, extensive requalification procedures, and excessive chemicalpurges. Such suggestions are not practical in semiconductormanufacturing with a need to reduced costs while maximizing throughput.

SUMMARY

An apparatus includes a chemical filter fluidly coupled between a sourcefor a processing solution and a nozzle to dispense the processingsolution. The chemical filter is configured to filter the processingsolution from the source. The apparatus may include a vacuum pump thatis configured to apply a vacuum to the chemical filter. The apparatusmay include a valve system configured to operate in a first operatingstate and a second operating state, where in the first operating statethe valve system is configured to couple the source to the chemicalfilter and block the vacuum to the chemical filter, and where in thesecond operating state the valve system is configured to couple thevacuum to the chemical filter and block the source to the chemicalfilter.

A method of supplying a processing solution includes shutting off a feedline supplying the processing solution to a chemical filter andinstalling a dry chemical filter in a filter housing of the chemicalfilter. The method may further include closing an output line from thefilter housing to a nozzle configured to dispense the processingsolution. The method may further include applying vacuum to the filterhousing. The method may further include opening the feed line whilelocking in the vacuum within the filter housing.

A device includes a memory storing a program to be executed in aprocessor. The program includes instructions to shut off a feed linesupplying a processing solution to a chemical filter. The program mayinclude instructions to close an output line from the filter housing toa nozzle configured to dispense the processing solution after installinga chemical filter in a filter housing of the chemical filter. Theprogram may include instructions to apply vacuum to the filter housing;and open the feed line while locking in the vacuum within the filterhousing.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a piping diagram of a filtration apparatus inaccordance with an embodiment of the present invention;

FIG. 2 is a flow diagram describing a process for replacing a chemicalfilter in accordance with an embodiment of the present invention;

FIGS. 3A-3C illustrate a cross sectional schematic magnifiedrepresentation of a chemical filter in accordance with an embodiment ofthe present invention, wherein FIG. 3A illustrates a filtration channelbeing blocked by air voids, wherein FIG. 3B illustrates a chemicalfilter before undergoing a vacuum assisted wetting process to remove airvoids, wherein FIG. 3C illustrates filtration channels being free of airvoids after undergoing a vacuum assisted wetting process;

FIG. 4 illustrates a piping diagram of a filtration apparatus inaccordance with an alternative embodiment of the present invention; and

FIGS. 5A-5B illustrate alternative configurations of a filtration systemusing electronic components to switch operating states in accordancewith an embodiment of the present invention.

The drawings are not necessarily drawn to scale. The drawings are merelyrepresentations, not intended to portray specific parameters of theinvention. The drawings are intended to depict only specific embodimentsof the inventions, and therefore should not be considered as limiting inscope. In the drawings, like numbering represents like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The structure, method, and using of various embodiments of a chemicalfiltration apparatus are discussed in detail below. However, it shouldbe valued that the various embodiments detailed herein may be applicablein a wide variety of disciplines. The specific embodiments describedherein are merely illustrative of specific ways to make and use variousembodiments, and should not be construed in a limited scope.

Air is introduced into the chemical dispense system through a wide arrayof manifestations. For example, it can occur during routine filterinstallation and removal procedures; through trapped air hidden withinplumbed chemical lines; through faulty O-rings generating weakened sealsamongst the filter manifold, housing, or support structures, thusallowing air to bleed into the filtration system; and/or throughdissolved gas within the processing solutions (i.e., photoresists,solvents, etc.)

Once air is introduced, it traverses the porous membrane of the chemicalfilter, becoming trapped within the filtration material comprised withinthe inner shell of the chemical filter. This in turn creates smallpockets of air voids that become difficult to dislodge throughconventional removal strategies. As the air pockets accumulate theycause blockages within the filtration channels. The blockages preventforeign matter from accessing the filtration channels. This negativelyaffects the wetting efficiency of the chemical filter, thus decreasingthe number of available the flow paths. Consequently, the blockedfiltration channels may give rise to a buildup of foreign material thatcan clog areas of the filtration material. Overtime, this build up canplace extra demand on any auxiliary pumps downstream of the chemicalfilter; can rupture the inner membrane of the filter; can furtherdowngrade the efficiency of the filter; and/or can decrease the lifetimeof the filter, thus prompting frequent filter replacements.

Embodiments of the present invention disclose a system and method thatuses vacuum to eliminate or reduce air voids. Accordingly, embodimentsof the present invention relate to a vacuum assisted filtration systemused to increase the wetting efficiency of chemical filters by removingair voids that block filtration channels. With increased wettingefficiency, cleaner processing solution may be dispensed so as toimprove product yield. An embodiment filtration apparatus will be firstdescribed using FIG. 1. Alternate embodiments of the filtrationapparatus will be first described using FIGS. 4, 5A-5B. A detailedprocess of using the filtration apparatus will be described using FIGS.2, and 3A-3C.

FIG. 1 illustrates a piping diagram of a filtration apparatus inaccordance with an embodiment of the present invention.

The filtration apparatus 30, in one or more embodiments, may be part ofa semiconductor processing tool. For example, the filtration apparatus30 may be part of a lithographic tool.

The filtration apparatus 30 comprises a source of inert gas 32 such asnitrogen (N₂) coupled to a source 31 of processing solution. Theprocessing solution 106, in various embodiments, may comprise chemicalsrelated to chemical processes involved in semiconductor processing thatrequire the use of filtration to maintain manufacturability. Theprocessing solution 106, in one or more embodiments, may comprisechemicals used in photolithography processes, wet cleaning processes,deposition process liquid precursor, or etching process liquidprecursor. The source 31 is configured to provide a processing solution106 and may include a holding tank and accompanying pumping equipment topump the processing solution 106. The source 31 may be enclosed within abottle, container, reservoir, or other enclosures. As an illustration,the source 31 may comprise bottles of plumbed solution disposed within aresist cart of a lithographic tool and coupled to further equipment asfurther discussed below.

Downstream of the source 31 is a valve system that comprises a firstcheck valve 36 a, followed by a three-way valve 33, then a second checkvalve 36 b. The second check valve 36 b is further coupled to a vacuum34 and its pumping system.

A manifold 35 is disposed downstream from the three-way valve 33. Themanifold 35 houses a chemical filter 102. A processing solution flowsthrough the chemical filter 102 and is filtered. In various embodiments,the manifold 35 may comprise a cylindrical housing within which thechemical filter 102 is mounted. The manifold 35 is fluidly coupled withthe nozzle 38 through a third check valve 36 c, a pump, and an airoperated valve (AOV) 37.

A resist (chemical) pump 41 is located downstream of the chemical filter102. The pump 41 is configured to move or pump the processing solution106, for example, by mechanical action. In various embodiments of theinvention, the type or classification of pump used in the system willlargely depend on the method by which it uses to move the fluid (i.e.,displacement, gravity, etc.). Nevertheless, the pump 41 helps to drawthe processing solution 106 from the chemical filter 102, e.g., bypositive displacement, and feed the processing solution 106 through thedispense line and into the nozzle 38.

The nozzle 38, which is at one end of the dispense line, is configuredto dispense the processing solution 106 to the surface of a wafer 39.The nozzle 38 and the wafer 39 may be placed within a chamber 42.

The air operated valve (AOV) 37 located in the dispense line between thenozzle 38 and the pump 41 may be used to electronically control thedispense quality of the processing solution 106 that exits the nozzle38. Examples of flow parameters set by the AOV 37 may include flow rateand fluid volume, suck back, and others.

According to embodiments of the vacuum assisted filtration apparatus 30,the manifold 35 comprises an input port such as input feed pipe. Theinput feed pipe is fluidly coupled to the source 31 and the vacuum 34and its pumping system. The manifold 35 further comprises an outlet portsuch as an output feed pipe that is fluidly coupled to the nozzle 38.The manifold 35 may also include an additional port such as an exhaustpipe designed to be coupled to an exhaust vent. The exhaust vent systemmay be coupled to the chemical filter 102. The function of the exhaustvent is to flush the processing solution 106 from the chemical linesleading up to, and possibly leading away from, the chemical filter 102.Thus, the processing solution 106 to be filtered enters the manifold 35through the input feed pipe and exits the manifold 35 through the outputfeed pipe.

Accordingly, the valve system comprises a first check valve 36 a, asecond check valve 36 b, a third check valve 36 c, a three-way valve 33,and an air operated valve (AOV) 37. In various embodiments, the valvesystem is configured to operate in a first operating state and a secondoperating state. In the first operating state, the valve system isconfigured to couple the source 31 to the chemical filter 102 and blockthe vacuum 34 and its pumping system from the chemical filter 102. Inthe second operating state, the valve system is configured to couple thevacuum 34 and its pumping system to the chemical filter 102 and blockthe source 31 from the chemical filter 102. During normal operation, thevalve system is operated in the first operating state. The valve systemis operating in the second operating state only during a filterreplacement operation or during a filter cleaning operation as will bedescribed in further detail below.

In one or more embodiments, the valve system may further comprise acontroller configured to switch the valve system from the firstoperating state to the second operating state. The controller could bethe three-way valve 33 in one embodiment. Or in various embodiments ofthe invention, the controller may comprise a solenoid valve, or anyother valve system currently known to those in the art.

In one or more embodiments of the vacuum assisted filtration apparatus30, the controller and its support components may be designed to operatemanually. Alternatively, in other embodiments the controller may be amicrocontroller or a microprocessor and may be designed to operateelectronically.

In various embodiments of this present invention, the filtrationapparatus 30 can be used with any aqueous materials including systemsthat filter water or pharmaceutical materials. In various embodiments ofthe filtration apparatus 30, the processing solution 106 may comprisesemiconductor processing solutions such as photoresist, polyimide liquidresin, deionized water, etchant, organic solvent, tetramethylammoniumhydroxide (TMAH), bottom layer anti-reflective coating (BARC),Si-containing anti-reflective coating (SiARC), top layer anti-reflectivecoating (TARC), immersion top coat, negative tone developer, and others.

A description of the operation of the filtration apparatus 30 duringfilter replacement will be described using FIG. 2.

FIG. 2 is a flow diagram describing a process for replacing a chemicalfilter in accordance with an embodiment of the present invention.

This flow diagram starts with a request to install a new chemical filterwithin the manifold 35, e.g., of the filtration apparatus 30 of FIG. 1.However, the actual process flow followed may be different depending onthe state of the filtration apparatus 30 and what is being intended tobe done. For example, when the filtration apparatus 30 is already inproduction and the filter has become dirty and is being replaced, no orlimited priming of the various distribution pipes/lines may beperformed. In particular, a priming process may not be performed whenthe solution being dispensed after the filter change continues to be thesame in a production process. This is because the various distributionpipes/lines are likely to be already clean. However, if the processingsolution being dispensed will be different after the filter change or ifthe filtration apparatus 30 is being installed in a new system (if it isnot a previously plumbed line) an initial priming process will beperformed so as to clean the various distribution pipes/lines.

Accordingly, an embodiment of the step S1 includes determining whetherpriming is to be performed. After making this determination, in casepriming is to be performed, this optional step S1 may involve followinga sequence of standard process steps but primarily involves continuallyflushing the dry line with a solvent so as to clean out foreign matter,wet the surfaces, remove air, etc. The solvent may be a differentcleaning solvent followed by priming with the processing solution 106 orjust done using the processing solution 106.

The priming of the chemical line may be performed upstream of themanifold 35 so as to not introduce processing solution 106 into themanifold 35. Alternatively, the priming may be performed with a dummyfilter (or with the older filter to be removed) so that the new filterto be installed is not coated with the processing solution 106.

In various embodiments, some or all the pipes between the source 31 andthe nozzle 38 may be repeatedly flushed with the solvent/processingsolution 106 during this step. Utilizing the filter vent and the filterbypass commands will ensure that none of the solvent/processing solution106 enters the older chemical filter 102 presently coupled to the line.

In preparation to remove this chemical filter 102, an embodiment of thestep S2 includes closing the older chemical filter 102 off from the feedline. In this step, the filtration apparatus 30 and in particular themanifold 35 is depressurized. For example, all the valves in the valvesystem such as the first check valve 36 a, a second check valve 36 b,and a third check valve 36 c are closed. This prevents or cuts-off theflow of solvent or the processing solution 106 in the manifold 35. Anyprocessing solution 106 in the manifold 35 or in the feed pipes isdrained off.

As next described in step S3, the older chemical filter 102 is safelyremoved and a newer, “dry” chemical filter 102 is installed to themanifold 305. A “dry” chemical filter 102 is devoid of liquid chemicals.During this process, the protective inlet/outlet caps on the new “dry”chemical filter 102 are removed and the new chemical filter 102 placedwithin the manifold 35. The chemical filter 102 is properly placed andsealed, e.g., using an O-ring, to ensure a tight fluid seal so thatthere is no leakage of the processing solution or gas when the system ispressurized again. In other words, there is no leakage from the chemicalfilter 102 into the outside from the manifold 35.

An embodiment of the step S4 includes initiating the vacuum 34 byapplying a negative pressure (relative to the pressure within thechemical filter 102). At this stage, the valve system is switched tooperate in the second operating state. After starting the vacuum, thefirst check valve 36 a and the third check valve 36 c remain closedwhile the second check valve 36 b is opened. The three-way valve 33 isthen switched manually or using a controller so that the vacuum 34 isnow coupled to the manifold 35. This removes/sucks the air from themanifold 35 and the newly installed chemical filter 102. In variousembodiments, the vacuum applied to the manifold 35 may reach a pressureinside the manifold 35 between 10 mTorr and 500 mTorr or lower pressuresso as to perform a successful process. As the vacuum 34 pumps down, itdraws ambient air from the “dry” chemical filter by applying a negativepressure. By monitoring the vacuum level, it is possible to determinewhen all of the air has been removed successfully from the chemicalfilter 102. Accordingly, once a steady vacuum is achieved, the vacuum304 and its external pump can be turned off.

While still holding vacuum 304, in step S5, the chemical filter 102 andmanifold 35 are closed off from the vacuum 304. This is done by closingthe second check valve 36 b and opening the first check valve 36 a andswitching the three-way valve 33 manually or using a controller so as tocouple the feed line to the manifold 35. Thus, the settings from filtervent and filter bypass are restored back to dispense line settings.

Referring next to step S6, the processing solution 106 is introduced tothe “dry” chemical filter 102. However, prior to this, the inert gas 32is depressurized to avoid having the processing solution 106 gush intothe chemical filter 102 so as to cause damage. For example, the pressureof the inert gas 32 may be reduced by a large magnitude, for example,from 50 Torr to 250 Torr in one illustration, or even an order ofmagnitude.

Referring next to step S7, the processing solution 106 is dispensed fromthe chemical source 31, through the chemical filter 102, and the pump 41out of the nozzle 38. Prior to dispensing the processing solution 106onto the wafer 39, the dispensing line between the manifold 35 and thenozzle 38 may be flushed. This may be performed in stages, for example,the pump 41 may be first flushed followed by the AOV 37 and the linesbetween the AOV 37 and the nozzle 38. This is to avoid any damage to thewafer 39 from foreign particles, air bubbles, or other debris. Afterflushing the dispensing line, the processing solution 106 may bedispensed around the wafer 39 into baths placed within the chamber 42,for example.

The wafer 39 is now ready to be processed by the processing solution 106and may be processed in accordance with the process recipe.

A detailed description of the working of the above process will beexplained using FIGS. 3A-3C. FIGS. 3A-3C illustrate a cross sectionalschematic magnified representation of a chemical filter in accordancewith an embodiment of the present invention.

In greater detail, and as illustrated schematically in FIG. 3A, thechemical filter 102 comprises a filtration material 104 that fills acompartmental shell within the chemical filter 102. In one illustration,the filtration material 104 may be a meshing of polymer fibers thatsieves foreign matter 103 (i.e., small particles, debris, extraneousparticulates, and others) from the processing solution 106.

As previously described, the processing solution 106 travels through thechemical filter 102 in the direction of flow designated by the arrow. Asthe processing solution 106 flows through the chemical filter 102, itmay include foreign matter 103. The foreign matter 103 immersed in theprocessing solution 106, follows a natural flow trajectory (designatedby the black trace line) along nonspecific (undefined) filtrationchannels 101.

Ideally, the filtration channels 101 are represented by clear, unblockedfluid pathways and openings within the filtration material 104. Thus,the foreign matter 103 would travel freely along the filtration channels101. However, in the absence of using the vacuum assisted change ofchemical filter as described in various embodiments of this application,the filtration channels 101 may include air voids 105. These may beintroduced during its manufacturing and packaging stages as well asintroduced at the time of the installing the chemical filter 102 intothe manifold 35.

Consequently, as the foreign matter 103 travels along the filtrationchannels 101, it may encounter air voids 105. The air voids 105 cause ablockage 108 (designated by the dashed lines in FIG. 3A) within thefiltration channels 101, thus interrupting the natural trajectory of theforeign matter 103 through the filtration material 104.

Depending on the concentration of the air voids 105 within thefiltration material 104, the number of clear, unblocked pathwaysdecrease so as to reduce the number of available filtration channels101. This decrease in the number of the filtration channels 101negatively impacts the wetting efficiency of the chemical filter 102. Inother words, the air voids 105 effectively reduce the surface area ofthe chemical filter 102 that the processing solution 106 contacts, whichreduces filtration efficiency.

FIG. 3B illustrates a chemical filter 102 before installation into themanifold 35. Ambient air 107 from the manufacturing/packaging surroundsthe filtration material 104.

In contrast, as depicted in FIG. 3B, using one or more embodiments ofinstalling the chemical filter 102, the concentration of air voids 105significantly reduces because of the use of vacuum 34 to suck up the airfrom the chemical filter 102. Unlike the prior illustration of FIG. 3A,because of the use of the external vacuum pump, the air voids 105 thatwould otherwise be formed within the chemical filter 102 are reduced.The external vacuum pump reduces the internal pressure within thechemical filter 102 by applying a negative pressure. The large negativepressure of the order of 10 mTorr and 500 mTorr efficiently removes theambient air 107.

Accordingly, once the processing solution 106 is introduced into theevacuated chemical filter 102 (which remains held at low pressurestate), the foreign matter 103 that is carried through the processingsolution 106 is able to travel more freely, without encountering ablockage 108 from the air voids 105. Absence of the air voids 105 withinthe filtration material 104 increases the number of filtration channels101 (as denoted by the black trace lines shown in FIG. 3C). Overall, thevacuum assistance improves the wettability of the chemical filter 102,thus increasing its efficiency at filtering the foreign matter 103 fromthe processing solution 106.

Accordingly, embodiments of the present application disclose using avacuum system to remove air from a newly added chemical filter. Forexample, after an optional priming process, the chemical line upstreamof the manifold 35 is closed off by the three-way valve 33, thuspreventing the flow of the processing solution 106.

With the chemical line closed off, the “dry” chemical filter 102 issafely installed. Once the “dry” chemical filter 102 is installed withinthe manifold 35, the vacuum 34 and its external pump can be initiated(as discussed in the step S4 of FIG. 2). As detailed above, as thevacuum 34 pumps down, ambient air 107 is drawn out from the “dry”chemical filter. Because the manifold 35 is airtight, the chemicalfilter 102 still maintains its low pressure state (i.e., it holds itscurrent vacuum level). At this stage, the three-way valve 33 istriggered to close off the vacuum 34 portion of the chemical line andopen the dispense line, thus returning the filtration system to itsoriginal settings (as discussed in the step S5).

In accordance with the steps S6-7, a positive pressure is appliedthrough the inert gas 32 to the chemical source 31. The positivepressure from the inert gas 32 draws the processing solution 106 fromthe chemical source 31. The processing solution 106 exits thepressurized source 31, traveling along the direction indicated by thearrows (see FIG. 1). Eventually the processing solution 106 reaches thefirst check valve 36 a. Once the processing solution 106 passes throughthe first check valve 36 a, it travels onto the three-way valve 33,which directs the processing solution 106 into the chemical filter 102that is housed within the manifold 35.

Since the chemical filter 102 (while still maintaining a designatedvacuum level) has been evacuated of the ambient air, the processingsolution 106 enters the chambers of the chemical filter 102.Consequently, the processing solution 106 fully wets the surface sincethe air voids 105 that once blocked the filtration channels 101 nolonger exist. This improved wetting efficiency resulting in a betterfiltering of the processing solution 106 from the foreign matter 103.The filtered processing solution 106 exits the chemical filter 102 anddispensed on the wafer 39 for further processing.

FIG. 4 illustrates a piping diagram of a filtration apparatus inaccordance with an alternative embodiment of the present invention. Thisembodiment differs in the configurations for the vacuum and its pumpingsystem.

In contrast to the vacuum configuration of FIG. 1, in which the vacuum34 is configured to be applied upstream of the chemical filter 102, inthis embodiment, the vacuum 34 is configured to be applied downstream ofthe chemical filter 102.

In this particular embodiment of the vacuum assisted filtrationapparatus 400, a vent trap 410 may be coupled to the secondconfiguration of the three-way valve 33. The vacuum 34 and its pumpingsystem are directly coupled to the manifold 35 (without going throughthe three-way valve 33) through the second check valve 36 b. All of thecomponents directly downstream of the chemical filter 102 may beconfigured in the same manner as described above in FIG. 1.

Despite of the alternate configuration of the vacuum 34 and its pumpingsystem, the process flow would still follow the same convention asdescribed above. As in the prior embodiment, in the first operatingstate, the first check valve 36 a will be opened and the three-way valve33 will fluidly couple the source 31 to the manifold 35. However, in thesecond operating state, the second check valve 36 b will be opened toconnect the vacuum 34 to the manifold 35 while the three-way valve 33will be coupled to the vent trap 41.

FIGS. 5A-5B illustrate alternate configurations of the piping diagramfor the vacuum assisted filtration apparatus 500 and 501, in whichelectronic components have been incorporated to switch operating states,all in accordance with an embodiment of the present invention. It shouldbe noted that in each embodiment illustrated in FIG. 5A-5B, theresulting arrangement of the vacuum 34 and its pumping system can takeon the various configurations as described above in FIG. 1 or 4.

These embodiments use electronic control to switch operating states,i.e., automatically connect/disconnect vacuum as well as to monitorvacuum and accomplish any of the other process steps discussed before.The electrical signal connections are illustrated in dashed lines to notconfuse with the fluid flow like that are indicated with solid lines.

In FIG. 5A, in alternate embodiments of vacuum assisted filtrationapparatus 500, the electronic control valves 46 a, 46 b, and 46 c arebeing controlled with a controller 511. Accordingly, in this embodiment,electronic control valves 46 a and 46 b are located on either sides ofthe three-way valve 33 and a third electronic control valve 46 c islocated on the exit side of the chemical filter 102. Additionally, auser interface 512 may be used to receive user input to initiate one ormore process steps. The input from the user interface 512 is sent to thecontroller 511, which may process them to generate separate controlsignals that are transmitted to synchronize the operation of the variouscomponents such as the three-way valve 33, the electronic control valves46 a, 46 b, and 46C, the vacuum 34, the pump 41, and the AOV 37.

FIG. 5B illustrates an alternate embodiment of the vacuum assistedfiltration apparatus 501 in which some of the valves may be check valvesas illustrated in this embodiment. In this embodiment, the electroniccontrol valves 46 a and 46 b are located on either sides of thethree-way valve 33 while a check valve 36 c is located on the exit sideof the chemical filter 102.

According to various embodiments of the invention, the vacuum assistedfiltration apparatus may comprise one or more processors, e.g.,represented as controller 511, and a memory 513 storing a program to beexecuted in a processor. In various embodiments, the program whenexecuted by the processor may perform the processes described in variousembodiments such as using FIG. 2.

In one or more embodiments, the program may further compriseinstructions to shut off a chemical feed line supplying a processingsolution 106 to the chemical filter 102. Additionally, afterinstallation of the chemical filter 102 within a manifold 35 (orhousing), the program may comprise instructions to close an outputchemical line from the manifold 35 to the nozzle 38. In otherembodiments, the program may give instructions to apply a vacuum 34 tothe chemical filter 102 and the manifold 35. The program may includefurther instructions to open the chemical feed lines while holding thevacuum 34 so it is maintained within the chemical filter 102.

In other embodiments, the program may comprise further instructions foropening the output chemical line after filling the chemical filter 102with processing solution 106. Likewise, the program may comprise furtherinstructions for venting the processing solution 106 before applying thevacuum 34 and its pumping system. The program may also comprise furtherinstructions for reaching a determined pressure inside the chemicalfilter 102 of between 10 mTorr and 500 mTorr.

Accordingly, application of the embodiments of the invention may reducethe volume of chemical required to fully wet a small pore sized filter,resulting in higher wetting volume efficiency. The result of higherwetting efficiency will reduce particles generated at the filtersurface, and reduce the amount of processing solution 106 used for aninstallation and requalification process. Advantageously, the filtrationsystem can be used with a plethora of aqueous materials.

Example embodiments of the invention are summarized here. Otherembodiments can also be understood from the entirety of thespecification as well as the claims filed herein.

Example 1. An apparatus includes a chemical filter fluidly coupledbetween a source for a processing solution and a nozzle to dispense theprocessing solution. The chemical filter is configured to filter theprocessing solution from the source. The apparatus may include a vacuumpump that is configured to apply a vacuum to the chemical filter. Theapparatus may include a valve system configured to operate in a firstoperating state and a second operating state, where in the firstoperating state the valve system is configured to couple the source tothe chemical filter and block the vacuum to the chemical filter, andwhere in the second operating state the valve system is configured tocouple the vacuum to the chemical filter and block the source to thechemical filter.

Example 2. The apparatus of example 1, further including: a controllerconfigured to switch the valve system from the first operating state tothe second operating state.

Example 3. The apparatus of one of examples 1 or 2, where the valvesystem includes a three-way valve that switches the valve system betweenthe first operating state and the second operating state.

Example 4. The apparatus of one of examples 1 to 3, where the chemicalfilter includes: a housing including a first port configured to becoupled to the source or the vacuum pump, a second port coupled to thenozzle, a third port coupled to an exhaust vent; and a filter disposedin the housing.

Example 5. The apparatus of one of examples 1 to 4, where the chemicalfilter includes: a housing including a first port coupled to the source,a second port coupled to the nozzle, a third port coupled to an exhaustvent, and a fourth port coupled to the vacuum pump; and a chemicalfilter disposed in the housing.

Example 6. The apparatus of one of examples 1 to 5, where the chemicalfilter includes: a housing including a first port configured to becoupled to the nozzle or the vacuum pump, a second port coupled to thesource, a third port coupled to an exhaust vent; and a chemical filterdisposed in the housing.

Example 7. The apparatus of one of examples 1 to 6, further including avent system coupled to the chemical filter, where the vent system isconfigured to flush the processing solution.

Example 8. A method of supplying a processing solution includes shuttingoff a feed line supplying the processing solution to a chemical filterand installing a dry chemical filter in a filter housing of the chemicalfilter. The method may further include closing an output line from thefilter housing to a nozzle configured to dispense the processingsolution. The method may further include applying vacuum to the filterhousing. The method may further include opening the feed line whilelocking in the vacuum within the filter housing.

Example 9. The method of example 8, further including opening the outputline after filling the filter housing with the processing solution.

Example 10. The method of one of examples 8 or 9, further includingremoving a used chemical filter from the filter housing beforeinstalling the dry chemical filter.

Example 11. The method of one of examples 8 to 10, further includingventing the processing solution before applying the vacuum.

Example 12. The method of one of examples 8 to 11, where the processingsolution includes chemicals for a photolithography process, wet cleaningprocess, deposition process liquid precursor, etching process liquidprecursor, or other chemical processes involved in semiconductor processthat use filtration to maintain manufacturability.

Example 13. The method of one of examples 8 to 12, where installing thechemical filter in the filter housing includes installing a dry chemicalfilter that is devoid of liquid chemicals before the installing.

Example 14. The method of one of examples 8 to 13, where applying thevacuum to the filter housing includes reaching a pressure inside thefilter housing between 10 mTorr and 500 mTorr.

Example 15. The method of one of examples 8 to 14, further includingprocessing a semiconductor wafer with the chemical dispensed from thenozzle.

Example 16. A device includes a memory storing a program to be executedin a processor. The program includes instructions to shut off a feedline supplying a processing solution to a chemical filter. The programmay include instructions to close an output line from the filter housingto a nozzle configured to dispense the processing solution afterinstalling a chemical filter in a filter housing of the chemical filter.The program may include instructions to apply vacuum to the filterhousing; and open the feed line while locking in the vacuum within thefilter housing.

Example 17. The device of example 16, where the program includes furtherinstructions for opening the output line after filling the filterhousing with the processing solution.

Example 18. The device of one of examples 16 or 17, where the programincludes further instructions for venting the processing solution beforeapplying the vacuum.

Example 19. The device of one of examples 16 to 18, where the programincludes further instructions for reaching a pressure inside the filterhousing between 10 mTorr and 500 mTorr, or lower pressures.

Example 20. The device of one of examples 16 to 19, further including aprocessor to execute the program.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. An apparatus comprising: a chemical filterfluidly coupled between a source for a processing solution and a nozzleto dispense the processing solution, the chemical filter configured tofilter the processing solution from the source; a vacuum pump configuredto apply a vacuum to the chemical filter; and a valve system configuredto operate in a first operating state and a second operating state,wherein in the first operating state the valve system is configured tocouple the source to the chemical filter and block the vacuum to thechemical filter, and wherein in the second operating state the valvesystem is configured to couple the vacuum to the chemical filter andblock the source to the chemical filter.
 2. The apparatus of claim 1,further comprising: a controller configured to switch the valve systemfrom the first operating state to the second operating state.
 3. Theapparatus of claim 1, wherein the valve system comprises a three-wayvalve that switches the valve system between the first operating stateand the second operating state.
 4. The apparatus of claim 1, wherein thechemical filter comprises: a housing comprising a first port configuredto be coupled to the source or the vacuum pump, a second port coupled tothe nozzle, a third port coupled to an exhaust vent; and a filterdisposed in the housing.
 5. The apparatus of claim 1, wherein thechemical filter comprises: a housing comprising a first port coupled tothe source, a second port coupled to the nozzle, a third port coupled toan exhaust vent, and a fourth port coupled to the vacuum pump; and achemical filter disposed in the housing.
 6. The apparatus of claim 1,wherein the chemical filter comprises: a housing comprising a first portconfigured to be coupled to the nozzle or the vacuum pump, a second portcoupled to the source, a third port coupled to an exhaust vent; and achemical filter disposed in the housing.
 7. The apparatus of claim 1,further comprising a vent system coupled to the chemical filter, whereinthe vent system is configured to flush the processing solution.
 8. Amethod of supplying a processing solution, the method comprising:shutting off a feed line supplying the processing solution to a chemicalfilter; installing a dry chemical filter in a filter housing of thechemical filter; closing an output line from the filter housing to anozzle configured to dispense the processing solution; applying vacuumto the filter housing; and opening the feed line while locking in thevacuum within the filter housing.
 9. The method of claim 8, furthercomprising opening the output line after filling the filter housing withthe processing solution.
 10. The method of claim 8, further comprisingremoving a used chemical filter from the filter housing beforeinstalling the dry chemical filter.
 11. The method of claim 8, furthercomprising venting the processing solution before applying the vacuum.12. The method of claim 8, wherein the processing solution compriseschemicals for a photolithography process, wet cleaning process,deposition process liquid precursor, or etching process liquidprecursor.
 13. The method of claim 8, wherein installing the chemicalfilter in the filter housing comprises installing a dry chemical filterthat is devoid of liquid chemicals before the installing.
 14. The methodof claim 8, wherein applying the vacuum to the filter housing comprisesreaching a pressure inside the filter housing between 10 mTorr and 500mTorr.
 15. The method of claim 8, further comprising processing asemiconductor wafer with the chemical dispensed from the nozzle.
 16. Adevice comprising: a memory storing a program to be executed in aprocessor, the program comprising instructions to shut off a feed linesupplying a processing solution to a chemical filter; after installing achemical filter in a filter housing of the chemical filter, close anoutput line from the filter housing to a nozzle configured to dispensethe processing solution; apply vacuum to the filter housing; and openthe feed line while locking in the vacuum within the filter housing. 17.The device of claim 16, wherein the program comprises furtherinstructions for opening the output line after filling the filterhousing with the processing solution.
 18. The device of claim 16,wherein the program comprises further instructions for venting theprocessing solution before applying the vacuum.
 19. The device of claim16, wherein the program comprises further instructions for reaching apressure inside the filter housing between 10 mTorr and 500 mTorr. 20.The device of claim 16, further comprising a processor to execute theprogram.